Organic food isn't noticeably better for people's health, according to a meta-analysis of past studies carried out by Stanford University scientists.
Organic foods have become big business over recent years, despite costing up to twice as much as their conventionally-grown counterparts. Between 1997 and 2011, US sales of organic foods increased from $3.6 billion to $24.4 billion.
Previous studies on the health benefits, though, have provided conflicting results, prompting what the Stanford team says is the most comprehensive meta-analysis to date.
What this reveals is that organic foods are no more nutritious than conventional alternatives and carry the same health risks, although consumption of organic foods can reduce the risk of pesticide exposure.
"There isn't much difference between organic and conventional foods, if you're an adult and making a decision based solely on your health," says researcher Dena Bravata.
No consistent differences were seen in the vitamin content of organic products, and only one nutrient — phosphorus — was significantly higher in organic versus conventionally grown produce. This isn't particularly important, as very few people have phosphorous deficiency.
There was also no difference in protein or fat content between organic and conventional milk, though evidence from some studies suggested that organic milk may contain significantly higher levels of omega-3 fatty acids.
The researchers were also unable to identify specific fruits and vegetables for which organic appeared the consistently healthier choice, despite running what Bravata calls 'tons of analyses'.
While researchers found that organic produce is 30 percent less likely to be contaminated with pesticides than conventional fruits and vegetables, organic foods still aren't always 100 percent free of pesticides. What's more, as the researchers noted, the pesticide levels of all foods fell within the allowable safety limits.
All this doesn't necessarily mean we should be abandoning the organic aisles, says Bravata, as many people may have taste preferences and concerns about the effects of conventional farming practices on the environment and animal welfare.
"If you look beyond health effects, there are plenty of other reasons to buy organic instead of conventional," she says.